The present invention relates to a method of limiting a closing force of a motorized opening on a sealing line of a motor vehicle, such as a window regulator window in a door seal, an opening/tilting roof, a motorized sliding side door, or a motorized swinging door (tailgate or trunk lid), etc.
In particular, a motorized window regulator makes it possible to open or close, by a window, an opening situated in a motor vehicle door. While the window is closing, a top edge of the window penetrates, for example, into a seal situated at a top of an opening of the door.
The force needed to raise the window in a door frame, called a transfer force, is roughly constant before the top edge of the window reaches the seal.
An additional force, called a closing force, is the force added to the transfer force to enable the top part of the window to penetrate into the seal in order to completely close the window, then to enable the seal to be squashed by the top edge of the window in order to ensure air and water tightness. The sum of the transfer force and the closing force is called a total force.
When the seal is squashed so that its reaction force no longer allows the window to advance, the window is subjected to a so-called blocking force. It is then at a top mechanical end stop.
However, the blocking force depends on the power supply voltage to the window regulator's electric motor. Thus, if the window is closed when the motor of the motor vehicle is switched off, the window has reached a mechanical end stop position. If the power supply voltage to the window regulator's electric motor is increased, for example when the engine of the motor vehicle is running, the blocking force increases. Now, because the window is in a mechanical end stop position, the increase in voltage is translated into an increase in the mechanical stresses on the components of the window regulator located between the window regulator's electric motor and the window, such as, for example, the sliders, and, for a cable-operated window regulator, the pulleys, the drum and the cables. This excess blocking force provides no additional benefit in the sealing process and unnecessarily limits the life of the window regulator. It is therefore advantageous to limit the closing force in order to increase the life of the window regulator.
The document U.S. Pat. No. 6,208,101 proposes a method for limiting surplus force of an electronically controlled window regulator when a top edge of a window abuts against a seal. This method includes the continuous detection of the positions of the window during the displacement of the window. This method also includes the recording of at least one measured value. This measured value is correlated with a total force applied to the window after a top edge of the window has entered to a depth of at least 25% of a seal area. The measured value is increased by a predetermined quantity to define a stop criterion so that the window regulator is stopped when this criterion is reached or exceeded. The stop criterion is therefore generated on the basis of at least one quantity measured after the top edge of the window has penetrated into the seal.
One drawback of this method is that the stop criterion depends on the total force applied to the window in the seal. In very cold weather, the total force applied to the window in the seal is very great. The closing force will not therefore be limited, or will be limited only very little in very cold weather, which means that the mechanical stresses on the components of the window regulator cannot be avoided.
There is therefore a need to limit the closing force regardless of the climatic or operating conditions of the motor vehicle.